@node Example
@section Example usage

Let's assume that there is some insecure link between your computer and
WiFi-reachable gateway.

@itemize
@item You have got @code{wlan0} NIC with 192.168.0/24 network on it.
@item You want to create virtual encrypted and authenticated 172.16.0/24
network and use it as a default transport.
@item @code{wlan0} MTU is 1500, 20 bytes overhead per IPv4. So MTU for
GoVPN is 1500 - 20 - 8 = 1472.
@item During startup client and server will say that TAP interface MTU
is 1432.
@end itemize

@strong{Install}. At first you must @ref{Installation, install} this
software: download, @ref{Integrity, check the signature}, compile.

@strong{Prepare the client}. Generate client's verifier for Alice as an
example:

@verbatim
client% ./utils/newclient.sh Alice
Enter passphrase:
Your client verifier is: $argon2d$m=4096,t=128,p=1$bwR5VjeCYIQaa8SeaI3rqg

Place the following JSON configuration entry on the server's side:

    "Alice": {
        "up": "/path/to/up.sh",
        "iface": "or TAP interface name",
        "verifier": "$argon2d$m=4096,t=128,p=1$bwR5VjeCYIQaa8SeaI3rqg$KCNIqfS4DGsBTtVytamAzcISgrlEWvNxan1UfBrFu10"
    }

Verifier was generated with:

    ./utils/storekey.sh /tmp/passphrase
    govpn-verifier -key /tmp/passphrase
@end verbatim

@strong{Prepare the server}. Add this entry to @code{peers.json}
configuration file:

@verbatim
{
    "Alice": {
        "iface": "tap10",
        "verifier": "$argon2d$m=4096,t=128,p=1$bwR5VjeCYIQaa8SeaI3rqg$KCNIqfS4DGsBTtVytamAzcISgrlEWvNxan1UfBrFu10"
    }
}
@end verbatim

@strong{Prepare network on GNU/Linux IPv4 server}:

@example
server% umask 077
server% ip addr add 192.168.0.1/24 dev wlan0
server% tunctl -t tap10
server% ip link set mtu 1432 dev tap10
server% ip addr add 172.16.0.1/24 dev tap10
server% ip link set up dev tap10
@end example

@strong{Run server daemon itself}:

@example
server% govpn-server -bind 192.168.0.1:1194 -mtu 1472
@end example

@strong{Prepare network on GNU/Linux IPv4 client}:

@example
client% umask 066
client% utils/storekey.sh key.txt
client% ip addr add 192.168.0.2/24 dev wlan0
client% tunctl -t tap10
client% ip link set mtu 1432 dev tap10
client% ip addr add 172.16.0.2/24 dev tap10
client% ip link set up dev tap10
client% ip route add default via 172.16.0.1
@end example

@strong{Run client daemon itself}:
@example
client% govpn-client \
    -key key.txt \
    -verifier '$argon2d$m=4096,t=128,p=1$bwR5VjeCYIQaa8SeaI3rqg' \
    -iface tap10 \
    -remote 192.168.0.1:1194 \
    -mtu 1472
@end example

@strong{FreeBSD IPv6 similar client-server example}:

@example
server% ifconfig em0 inet6 fe80::1/64
server% govpn-server -bind "fe80::1%em0"
@end example

@example
client% ifconfig me0 inet6 -ifdisabled auto_linklocal
client% ifconfig tap10
client% ifconfig tap10 inet6 fc00::2/96 mtu 1412 up
client% route -6 add default fc00::1
client% govpn-client \
    -key key.txt \
    -verifier '$argon2d$m=4096,t=128,p=1$bwR5VjeCYIQaa8SeaI3rqg' \
    -iface tap10 \
    -remote "[fe80::1%me0]":1194
@end example